The present invention generally relates to a liquid jet recording head, and more particularly to a liquid jet recording head in which liquid drops are jetted through orifices by using vibration of piezo-electric elements.
A liquid jet recording apparatus, such as a conventional on-demand-type ink jet recording apparatus, has a piezo-electric actuator. It is difficult to increase integration density of the conventional recording head. Even if an integration density is increased a driving voltage of the piezo-electric actuator must be also increased.
The following documents disclose recording heads directed to improving the disadvantage described above.
Japanese Patent Publication No. 60-8953 discloses a recording head in which a piezo-electric actuator is provided in ink and opposed to a nozzle, ink drops are jetted from the nozzle due to driving of the piezo-electric. In Japanese Laid-Open Patent Application No. 63-252750, a recording head is disclosed in which the piezo-electric actuator drives partition walls of a flow path having ink and so ink drops are jetted from the flow path. In Japanese Laid-Open Patent Application No. 59-159358, a recording head is proposed in which walls of the flow path having ink are formed on piezo-electric blocks. Then, due to vibrations of the piezo-electric blocks, ink is jetted from the flow path. In a recording head disclosed in Japanese Laid-Open Patent Application No. 62-56150, grooves which are arranged in parallel with each other are formed as flow paths of ink on a piezo-electric plate. U.S. Pat. No. 4,072,959 discloses a recording head in which a pusher pin is provided adjacent to an orifice and ink which exists near the orifice is jetted through the orifice due to a bending displacement of the pusher pin. In addition, in "IMC 1986 Proceeding Kobe." (May 28-30 1986), a recording head having a piezo-electric member is disclosed. The piezo-electric member has layered green sheets. A cavity portion is provide in the layered green sheets. Ink drop is jetted from the cavity portion, when a displacement in the piezo-electric member is produced due to a bending moment of the piezo-electric member.
Japanese Laid-Open Patent Application No. 60-90770 disclosed a recording head as shown in FIG. 1. In FIG. 1, grooves 11 are formed in a parallel form with each other on a piezo-electric plate 1. Thus, in the piezo-electric plate 1, a piezo-electric element (hereinafter simply referred to as element) 1a is formed between two of the grooves 11. Each of the elements 1a can vibrate independently. A flow path plate 2 has a plurality of flow paths 9 which are arranged in parallel with each other. Each of the flow paths 9 is a groove formed on the flow path plate 2, and ink is supplied to the groove (i.e. the flow path) from an external ink supplier (not shown in FIG. 1). A vibration plate 12 is sandwiched between the piezo-electric plate 1 and the flow path plate 2 so that an end of each element 1a opposes to one of the flow path 9.
Vibration of each of the elements 1a is transmitted via the vibration plate 12 to ink in the corresponding flow path 9 so that ink drops are jetted from the flow path 9 through an orifice (not shown in FIG. 1).
In the conventional recording head as is shown in FIG. 1, it is possible to increase integration density, since a plurality of the vibration elements 1a, each being a driving source to jet ink drops, are formed by forming of a plurality of grooves 11 on the piezo-electric plate 1. Then, it is also easy to form vibration elements 1a.
However, there is the possibility of warping of the flow path plate 2, since a force which is caused by vibration of elements 1a adds via the vibration plate 12 to the whole surface of the flow path plate 2, which contacts with the vibration plate 12.
In addition, the vibration of each of the elements 1a transmits via the vibration plate 12 to the corresponding flow path 9 so that it is difficult to obtain sufficient changing of the volume in the flow path 9. Thus, it is necessary to increase the driving voltage of the piezo-electric plate 1.